Data backup method in a network storage system

Abstract

In a data backup method in a network storage system in which mirroring is conducted between two disk units, the mirroring is delayed by accumulating update data in a cache for a predetermined period of time. When storing the update data in the cache, files are related to each other, and information of file open and close is also stored. The update data is reflected in the mirrored disk using the file open and close information. As a result, the contents of the mirrored disk are delayed for a predetermined period of time from those of the primary disk, and all files are in other than the open state. Within a range of the period to store data in the cache, it is possible to restore data created at a point of time preceding a desired period of time. This enables recovery if a user erases files by mistake.

1. The information processing system An information processing system, comprising:
 a processor; 
 a first storage apparatus which can be accessed by the processor; 
 a second storage apparatus which can be accessed by the processor; and 
 a third storage apparatus, wherein 
 the processor includes a control unit for conducting a backup operation from the first storage apparatus to the second storage apparatus, 
 the third storage apparatus includes an update log of the first storage apparatus and file open and close information for the first storage apparatus, and 
 the control unit conducts a rewriting operation in the second storage apparatus using the update log and the file open and close information of the first storage apparatus, 
 wherein the control unit prevents a write operation of a file, which is not closed after the file is opened, in the second storage apparatus using the update log of the first storage apparatus and information regarding an opening and closing time of the file of the first storage apparatus. 
 
   
   
     2. The information processing system according to  claim 1 , wherein the update log of the first storage apparatus includes a location to store information indicating contents of update, and time of update. 
   
   
     3. The information processing system according to  claim 1 ,
 wherein the control unit extracts, from the update log, an update log item having an update time at least a predetermined time before and conducts the back up operation using the extracted update log items.